I have to make changes into a VB 6 application that includes interface13m (Ariad Interface Components 1.3) but it fails to install correctly... I know it`s normal as it has been a while since this product was published! However, as its not an option for me to not use it this time again, I am asking for your help.

This is what I think should have made the ocx file to register correctly:

I don't think I'd ever recommend turning UAC off, just running cmd as admin should have been sufficient.

Seems a bit strange that it doesn't work - after all, the VB6 runtime is still supported and must work in 64bit. Hell, I know it does because I have another machine (Windows 10 64bit) that has a VB5 application running on it!

As none of my VM's are 64bit, I extracted the old demo program and the OCX from backups and stuck them on my freshly-upgraded Windows 10 Pro machine as this is 64bit. With UAC enabled

I registered the OCX via an admin command prompt, then ran the demo. To my utter shock it actually runs!

Anyway, it runs for me, which doesn't exactly help you. However, I just ran regsvr32.exe and allowed it to be used via the path. When I did a WHERE regsvr32.exe it reported that it was being run from System32 - maybe you could try running that version rather than the SysWOW64 version?